dotfiles/.config/shell/rc.d/ssh-agent-autoconfiguration.sh

#!/bin/sh

## Integration at the Bottom

# Copyright (C) 2011 by Wayne Walker <wwalker@solid-constructs.com>
#
# Released under one of the versions of the MIT License.
#
# Copyright (C) 2011 by Wayne Walker <wwalker@solid-constructs.com>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

_LIVE_AGENT_LIST=""
declare -a _LIVE_AGENT_SOCK_LIST
_LIVE_AGENT_SOCK_LIST=()

_debug_print() {
  if [[ $_DEBUG -gt 0 ]]; then
    printf "%s\n" $1
  fi
}

find_all_ssh_agent_sockets() {
  _SSH_AGENT_SOCKETS=$(find /tmp/ -type s -name agent.\* 2>/dev/null | grep '/tmp/ssh-.*/agent.*')
  _debug_print "$_SSH_AGENT_SOCKETS"
}

find_all_gpg_agent_sockets() {
  _GPG_AGENT_SOCKETS=$(find /tmp/ -type s -name S.gpg-agent.ssh 2>/dev/null | grep '/tmp/gpg-.*/S.gpg-agent.ssh')
  _debug_print "$_GPG_AGENT_SOCKETS"
}

find_all_gnome_keyring_agent_sockets() {
  _GNOME_KEYRING_AGENT_SOCKETS=$(find /tmp/ -type s -name ssh 2>/dev/null | grep '/tmp/keyring-.*/ssh$')
  _debug_print "$_GNOME_KEYRING_AGENT_SOCKETS"
}

find_all_osx_keychain_agent_sockets() {
  [[ -n "$TMPDIR" ]] || TMPDIR=/tmp
  _OSX_KEYCHAIN_AGENT_SOCKETS=$(find $TMPDIR/ -type s -regex '.*/ssh-.*/agent..*$' 2>/dev/null)
  _debug_print "$_OSX_KEYCHAIN_AGENT_SOCKETS"
}

test_agent_socket() {
  local SOCKET=$1
  SSH_AUTH_SOCK=$SOCKET ssh-add -l 2>/dev/null >/dev/null
  result=$?

  _debug_print $result

  if [[ $result -eq 0 ]]; then
    # contactible and has keys loaded
    _KEY_COUNT=$(SSH_AUTH_SOCK=$SOCKET ssh-add -l | wc -l | tr -d ' ')
  fi

  if [[ $result -eq 1 ]]; then
    # contactible butno keys loaded
    _KEY_COUNT=0
  fi

  if [[ (($result -eq 0) || ($result -eq 1)) ]]; then
    if [[ -n "$_LIVE_AGENT_LIST" ]]; then
      _LIVE_AGENT_LIST="${_LIVE_AGENT_LIST} ${SOCKET}:$_KEY_COUNT"
    else
      _LIVE_AGENT_LIST="${SOCKET}:$_KEY_COUNT"
    fi
    return 0
  fi

  return 1
}

find_live_gnome_keyring_agents() {
  for i in $_GNOME_KEYRING_AGENT_SOCKETS; do
    test_agent_socket $i
  done
}

find_live_osx_keychain_agents() {
  for i in $_OSX_KEYCHAIN_AGENT_SOCKETS; do
    test_agent_socket $i
  done
}

find_live_gpg_agents() {
  for i in $_GPG_AGENT_SOCKETS; do
    test_agent_socket $i
  done
}

find_live_ssh_agents() {
  for i in $_SSH_AGENT_SOCKETS; do
    test_agent_socket $i
  done
}

function fingerprints() {
  local file="$1"
  while read l; do
    [[ -n $l && ${l###} == $l ]] && ssh-keygen -l -f /dev/stdin <<<$l
  done <$file
}

find_all_agent_sockets() {
  _SHOW_IDENTITY=0
  if [ "$1" = "-i" ]; then
    _SHOW_IDENTITY=1
  fi
  _LIVE_AGENT_LIST=
  find_all_ssh_agent_sockets
  find_all_gpg_agent_sockets
  find_all_gnome_keyring_agent_sockets
  find_all_osx_keychain_agent_sockets
  find_live_ssh_agents
  find_live_gpg_agents
  find_live_gnome_keyring_agents
  find_live_osx_keychain_agents
  _debug_print "$_LIVE_AGENT_LIST"
  _LIVE_AGENT_LIST=$(echo $_LIVE_AGENT_LIST | tr ' ' '\n' | sort -n -t: -k 2 -k 1 | uniq)
  _LIVE_AGENT_SOCK_LIST=()
  _debug_print "SORTED: $_LIVE_AGENT_LIST"
  if [ -e ~/.ssh/authorized_keys ]; then
    _FINGERPRINTS=$(fingerprints ~/.ssh/authorized_keys)
  fi
  if [[ $_SHOW_IDENTITY -gt 0 ]]; then
    i=0
    for a in $_LIVE_AGENT_LIST; do
      sock=${a/:*/}
      _LIVE_AGENT_SOCK_LIST[$i]=$sock
      # technically we could have multiple keys forwarded
      # But I haven't seen anyone do it
      akeys=$(SSH_AUTH_SOCK=$sock ssh-add -l)
      key_size=$(echo ${akeys} | awk '{print $1}')
      fingerprint=$(echo ${akeys} | awk '{print $2}')
      remote_name=$(echo ${akeys} | awk '{print $3}')
      if [ -e ~/.ssh/authorized_keys ]; then
        authorized_entry=$(fingerprints ~/.ssh/authorized_keys | grep $fingerprint)
      fi
      comment=$(echo ${authorized_entry} | awk '{print $3,$4,$5,$6,$7}')
      printf "export SSH_AUTH_SOCK=%s \t#%i) \t%s\n" "$sock" $((i + 1)) "$comment"
      i=$((i + 1))
    done
  else
    printf "%s\n" "$_LIVE_AGENT_LIST" | sed -e 's/ /\n/g' | sort -n -t: -k 2 -k 1
  fi
}

set_ssh_agent_socket() {
  if [ "$1" = "-c" -o "$1" = "--choose" ]; then
    find_all_agent_sockets -i

    if [ -z "$_LIVE_AGENT_LIST" ]; then
      echo "No agents found"
      return 1
    fi

    echo -n "Choose (1-${#_LIVE_AGENT_SOCK_LIST[@]})? "
    read choice
    if [ -n "$choice" ]; then
      n=$((choice - 1))
      if [ -z "${_LIVE_AGENT_SOCK_LIST[$n]}" ]; then
        echo "Invalid choice"
        return 1
      fi
      echo "Setting export SSH_AUTH_SOCK=${_LIVE_AGENT_SOCK_LIST[$n]}"
      export SSH_AUTH_SOCK=${_LIVE_AGENT_SOCK_LIST[$n]}
    fi
  else
    # Choose the first available
    SOCK=$(find_all_agent_sockets | tail -n 1 | awk -F: '{print $1}')
    if [ -z "$SOCK" ]; then
      return 1
    fi
    export SSH_AUTH_SOCK=$SOCK
  fi

  # set agent pid
  if [ -n "$SSH_AUTH_SOCK" ]; then
    export SSH_AGENT_PID=$(($(echo $SSH_AUTH_SOCK | cut -d. -f2) + 1))
  fi

  return 0
}

ssh-find-agent() {
  if [ "$1" = "-c" -o "$1" = "--choose" ]; then
    set_ssh_agent_socket -c
    return $?
  elif [ "$1" = "-a" -o "$1" = "--auto" ]; then
    set_ssh_agent_socket
    return $?
  else
    find_all_agent_sockets -i
    return 0
  fi
}

# Automatically add ssh-agent to any new ssh connection
ssh-find-agent -a
if [ -z "$SSH_AUTH_SOCK" ]; then
  eval $(ssh-agent) >/dev/null
  ssh-add -l >/dev/null || alias ssh='ssh-add -l >/dev/null || ssh-add && unalias ssh; ssh'
fi